For the record, safer auto-compressed output will add about 69 bytes after gzip. We can save more than half of that (+26) by comparing against a global variable instead of literal "undefined", and we can do it without waiting on dependency upgrades. Expect something along those lines later this week.

As an interesting side note, minification also undoes some of our performance micro-optimizations, replacing undefined/true/false respectively with void 0/!0/!1 and making typeof comparisons loose (e.g., "string"==typeof v instead of "string"===typeof v).

I haven't checked on the latter size optimization, but the former is configurable and saves something like 40 bytes after gzip.

Also interesting, but probably not actionable, is that minification maps our internal variable jQuery to a two-character identifier. Swapping it with a one-character identifier would save another 40 bytes gzipped.